Annulated rotor



1965 J. WAG MAN 3,219,266

ANNULATED ROTOR Original Filed Feb. 26, 1960 ack Magma/1 BY aw y. f? vUnited States Patent 3,219,266 ANNULATED ROTOR Jack Wagman, Frederick,Md., assignor to the United States of America as represented by theSecretary of the Army Filed Dec. 4, 1963, Ser. No. 328,134

3 Claims. (Cl. 23328) (Granted under Title 35, U.S. Code (1952), sec.266) The invention described herein may be manufactured and used by orfor the Government of the United States of America for governmentalpurposes without the payment to me of any royalty thereon.

This invention relates to a new and improved rotor for a centrifuge. Inthe past when it was desired to separate particulate matter from a solidsuspension in a liquid, it was necessary to pour the material intocentrifuge tubes, insert the tubes into a holder in the centrifugerotor, accelerate the rotor to the desired speed, wait until there is aseparation, decelerate the rotor, remove the tubes from the rotor,without disturbing the well defined layers, a task which is rather hardto accomplish, and finally separate the two components being careful notto mix the two phases. Another inherent disadvantage of this method isthat the two phases are in contact with each other during the entireoperation.

The present rotor allows a complete physical separation, almostinstantaneously, and not just a separation into two layers, therebyeliminating the danger of the two phases being remixed.

This rotor can also separate intermediate reaction products. Theseproducts exist for only a short time because their continued contactwith the other constituents causes the reaction to go to completionthereby destroying the intermediates. Since this rotor can physicallysepa rate these phases from contact with each other almostinstantaneously, these intermediate products can be separated andcollected before they are destroyed by further reactions. This apparatuscan separate two or more immiscible liquids, or suspended solids from aliquid.

Because this rotor can make actual physical separations, it can be usedas an analytical tool to study the kinetics of enzyme reactions, and tostudy rates of adsorption or penetration of ions into bacterial cells orother living material. Many other analytical uses of similar nature canbe devised using this new rotor. This rotor can be easily adapted foruse on any standard centrifuge.

The drawing shows a section of a side elevational view of this rotor.

The rotor is coupled to the drive unit of the centrifuge in the standardfashion by means of pins 12 which are contained in recess 14. Bowl 16 isfound in the upper center portion of the rotor. The bowl is open at thetop and is bounded by conical side wall 17 and bottom wall 18. Thebottom portion of side wall 17 does not join directly with bottom wall18 but there is a recess 19 which extends under side wall 17 for somedistance. Within side wall 17 there are a number of channels 20 spacedfrom each other. These channels are in communication with recess 19 andpreferably extend upwardly at approximately 60 from the horizontal. Theangle of the channels is not critical and may be anywhere between 0 and90. The upper or outer ends of channels 20 open at 21 into annularrecess 22. A projection wall 24 extends inwardly and above the lowerannular recess or indentation and provides a partition between theannular indentation 22 and the upper annular indentation 26. Theseannular indentations may be made of a size and shape to accommodate theparticular needs.

In operation the rotor is spinning within the centrifuge, for example at10,000 r.p.m. A liquid with suspended solids, for example, is introducedat a suitable rate into 3,219,266 Patented Nov. 23, 1965 the bottom ofthe bowl where it is immediately thrown to the outer limits of the bowl,that is to the recess 19. The suspension is forced up the channels andthereby instantly acquires the same speed of rotation as that of therotor. After passing through the channels 20, the suspension enters thelower annular indentation. As the latter becomes filled with suspensionthe heavier solids are crowded into its outer portion and clearsupernatant fluid is formed at the inner surface of the liquid layercloser to the axis of rotation. Further introduction of suspensionresults in a flow of clear supernatant fluid over projection wall 24 andinto upper annular indentation 26. After the required amount of clearsupernatant fluid collects in the upper annular indentation 26, therotor is decelerated. With the rotor at rest, cleared supernatant fluidcan be drawn off with a pipette or syringe from the upper annularindentation 26, and if desired the packed solid can be scraped from thelower annular indentation.

The example of separation of solid and liquid given above can be aidedadditionally by use of an inert liquid of an intermediate density. Forexample, bacteria which has the density of 1.08 can be separated fromwater having a density of 1.00. In this case it is advantageous to use awater-immiscible liquid such as dibutyl phthalate having an intermediatedensity of 1.046 in order to attain a clear cut physical separation.This operation is accomplished in the following manner: the dibutylphthalate is introduced into the spinning rotor so that the lowerannular indentation is partially filled; the mixture of water andbacteria is introduced into the rotating rotor at a suitable rate; thebacteria being heavier than the dibutyl phthalate replaces it in theouter portion of the lower indentation, and the water being lighter thanthe phthalate is pushed by the continued introduction of the mixturetoward the end of the projection wall and around it into the upperindentation; the dibutyl phthalate remains in between the water layerand the bacterial layer. Thus it can be seen that by using aninterposing liquid, two significant advantages can be obtained: (1) itreduces the volume of mixture required to recover the desired amount ofsupernatant liquid, and (2) it aids in the complete physical separationbetween the solid sediment and the supernatant liquidin other words, itacts as a barrier to contact between the water and bacteria.

An example of how this rotor can be used as an analytical device willnow be explained. It is often desirable to know the kinetics of ionpenetration into living cells, that is the rate of penetration and theextent of the penetration of the ions into the cell. This can be easilydetermined using my rotor. For example, a water suspension of bacteriaand a salt solution, for example MgSO, in H O, are simultaneouslyintroduced into a mixing chamber at predetermined rates. After rapid andthorough mixing, the flow of mixture is directed into the rotatingrotor, whereupon there is a rapid separation of the salt solution andthe cells, the salt solution being recoverable from the upper annulusand the cells from the lower indentation. The salt solution is analyzedfor anion or cation concentration and is compared with the starting saltsolution concentration, taking into consideration the dilution with thewater from the cell water suspension. The mixing time may be determinedaccurately by employing interacting materials with known rates ofreaction in a control test using the same flow rates. The rates andextent of penetration can therefore be easily determined from the dataobtained. The kinetics of enzyme-substrate reactions can be determinedsimilarly.

A centrifuge with this new improved rotor obviously could easily bemodified to provide means for a continuous withdrawal of materials fromthe lower and upper annuli.

Many other applications besides those mentioned herein can be devised inthe employment of this new rotor. I claim:

1. A centrifugal separating device comprising a rotor, said rotorcomprising;

fluid separating bowl means having entry means so that fluid may beintroduced thereinto, the fluid separating means comprising,

a bottom in the bowl, distributor means consisting of at least one fluidpassage means extending from the bottom of the bowl at one end anddischarging into a first annular recess in the bowl at its other end,the annular recess being radially outward of the bottom, the annularrecess receiving a mixture of heavy and light components from thechannels and separating said mixture with the heavy component beingoutermost, the first annular recess having an annular wall extendingradially inwardly over the lip of which the light component spills, anda second annular recess on the other side of light component as itspills over the annular wall and.

to retain the light component therein as rotation of the rotor ceases.

3. Apparatus as set forth in claim 1, the fluid passage means extendingaxially and radially from the bottom.

References Cited by the Examiner UNITED STATES PATENTS 585,936 7/1897Linders 23328 2,472,475 6/1949 Hamilton 233-27 X 2,840,303 6/1958 Stuart233-28 M. CARY NELSON, Primary Examiner.

HENRY T. KLINKSIEK, Examiner.

1. A CENTRIFUGAL SEPARATING DEVICE COMPRISING A ROTOR, SAID ROTORCOMPRISING; FLUID SEPARATING BOWL MEANS HAVING ENTRY MEANS SO THAT FLUIDMAY BE INTRODUCED THEREINTO, THE FLUID SEPARATING MEANS COMPRISING, ABOTTOM IN THE BOWL, DISTRIBUTOR MEANS CONSISTING OF AT LEAST ONE FLUIDPASSAGE MEANS EXTENDING FROM THE BOTTOM OF THE BOWL AT ONE END ANDDISCHARGING INTO A FIRST ANNULAR RECESS IN THE BOWL AT ITS OTHER END,THE ANNULAR RECESS BEING RADIALLY OUTWARD OF THE BOTTOM, THE ANNULARRECESS RECEIVING A MIXTURE OF HEAVY AND LIGHT COMPONENTS FROM THECHANNELS AND SEPARATING SAID MIXTURE WITH THE HEAVY COMPONENT BEINGOUTERMOST,